Re: [PATCH] imsm: fix: correct checking volume's degradation

[NeilBrown <neilb@suse.de>]

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On Fri, 25 May 2012 15:06:41 +0200 Lukasz Dorau <lukasz.dorau@intel.com>
wrote:

> We do not check the return value of sysfs_get_ll() now. It is wrong.
> If reading of the sysfs "degraded" key does not succeed,
> the "new_degraded" variable will not be initiated
> and accidentally it can have the value of "degraded" variable.
> In that case the change of degradation will not be checked.
> 
> It happens if mdadm is compiled with gcc's "-fstack-protector" option
> when one tries to stop a volume under reshape (e.g. OLCE).
> Reshape seems to be finished then (metadata is in normal/clean state)
> but it is not finished, it is broken and data are corrupted.
> 
> Now we always check the return value of sysfs_get_ll().
> Even if reading of the sysfs "degraded" key does not succeed
> (rv == -1) the change of degradation will be checked.
> 
> Signed-off-by: Lukasz Dorau <lukasz.dorau@intel.com>
> ---
>  super-intel.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/super-intel.c b/super-intel.c
> index 6c87e20..07ab9ae 100644
> --- a/super-intel.c
> +++ b/super-intel.c
> @@ -10370,8 +10370,10 @@ int check_degradation_change(struct mdinfo *info,
>  			     int degraded)
>  {
>  	unsigned long long new_degraded;
> -	sysfs_get_ll(info, NULL, "degraded", &new_degraded);
> -	if (new_degraded != (unsigned long long)degraded) {
> +	int rv;
> +
> +	rv = sysfs_get_ll(info, NULL, "degraded", &new_degraded);
> +	if ((rv == -1) || (new_degraded != (unsigned long long)degraded)) {
>  		/* check each device to ensure it is still working */
>  		struct mdinfo *sd;
>  		new_degraded = 0;


applied, thanks.

NeilBrown


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